A hybrid vehicle is known that has (a) a direct injection engine directly injecting fuel into a cylinder, (b) a clutch connecting/disconnecting (coupling/interrupting) the direct injection engine to/from a power transmission path, and (c) a rotating machine at least acting as an electric motor and (d) that can use the direct injection engine and the rotating machine as a drive power source for running. A hybrid vehicle described in Patent Document 1 is an example thereof and, during motor running using only the rotating machine as the drive power source for running, a friction clutch is connected (frictionally engaged) to rotate and adjust a crankshaft of the direct injection engine such that a crank angle in a cylinder in an expansion stroke falls within a predetermined range so as to inject fuel into the cylinder in the expansion stroke for ignition at the time of engine start in a described technique of ignition start. Patent Document 2 relates to an engine drive vehicle including a direct injection engine and, when idling is stopped (engine is stopped) during vehicle stop, a crank angle of a cylinder in an expansion stroke at the time of engine stop is put into a predetermined angle range enabling ignition start by output adjustment through electric generation (rotation load) by an alternator and throttle control in preparation of the next engine start in a described technology.
Although the engine can start by itself only with the ignition start in some cases such as when friction of the direct injection engine is small, the clutch can be connected at the time of engine start as needed to assist cranking with the rotating machine, and assist torque can significantly be reduced by the ignition start. As a result, maximum torque of the rotating machine can be reduced to achieve reduction in size and fuel consumption.